Category

Description

Skeletal muscle relaxants are used to relax certain muscles in your body and relieve the stiffness, pain, and discomfort caused by strains, sprains, or other injury to your muscles. However, these medicines do not take the place of rest, exercise or physical therapy, or other treatment that your doctor may recommend for your medical problem. Methocarbamol also has been used to relieve some of the muscle problems caused by tetanus.

Skeletal muscle relaxants act in the central nervous system (CNS) to produce their muscle relaxant effects. Their actions in the CNS may also produce some of their side effects.

In the U.S., these medicines are available only with your doctor"s prescription. In Canada, some of these medicines are available without a prescription.

These medicines are available in the following dosage forms:

Oral

Carisoprodol

Tablets (U.S. and Canada)

Chlorphenesin

Tablets (U.S.)

Chlorzoxazone

Tablets (U.S.)

Metaxalone

Tablets (U.S.)

Methocarbamol

Tablets (U.S. and Canada)

Parenteral

Methocarbamol

Injection (U.S. and Canada)

Before Using This Medicine

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For the skeletal muscle relaxants, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to any of the skeletal muscle relaxants or to carbromal, mebutamate, meprobamate (e.g., Equanil), or tybamate. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Although skeletal muscle relaxants have not been shown to cause birth defects or other problems, studies on birth defects have not been done in pregnant women. Studies in animals with metaxalone have not shown that it causes birth defects.

Breast-feeding—Carisoprodol passes into the breast milk and may cause drowsiness or stomach upset in nursing babies. It is not known whether chlorphenesin, chlorzoxazone, metaxalone, or methocarbamol passes into the breast milk. However, these medicines have not been reported to cause problems in nursing babies.

Children—Studies with the skeletal muscle relaxants have been done only in adult patients, and there is no specific information comparing use of these medicines in children with use in other age groups. However, carisoprodol and chlorzoxazone have been used in children. They have not been reported to cause different side effects or problems in children than they do in adults.

Older adults—Many medicines have not been tested in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults or if they cause different side effects or problems in older people. There is no specific information about the use of skeletal muscle relaxants in the elderly.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking a skeletal muscle relaxant, it is especially important that your health care professional know if you are taking any of the following:

Other medical problems—The presence of other medical problems may affect the use of a skeletal muscle relaxant. Make sure you tell your doctor if you have any other medical problems, especially:

Allergies, history of, or

Blood disease caused by an allergy or reaction to any other medicine, history of, or

Drug abuse or dependence, or history of, or

Kidney disease or

Liver disease or

Porphyria—Depending on which of the skeletal muscle relaxants you take, the chance of side effects may be increased; your doctor can choose a muscle relaxant that is less likely to cause problems

Epilepsy—Convulsions may be more likely to occur if methocarbamol is given by injection

Proper Use of This Medicine

Chlorzoxazone, metaxalone, or methocarbamol tablets may be crushed and mixed with a little food or liquid if needed to make the tablets easier to swallow.

Dosing—The dose of these medicines will be different for different patients. Follow your doctor"s orders or the directions on the label . The following information includes only the average doses of these medicines. If your dose is different, do not change it unless your doctor tells you to do so.

For carisoprodol

For oral dosage form (tablets):

For relaxing stiff, sore muscles:

Adults and teenagers—350 milligrams (mg) four times a day.

Children up to 5 years of age—Dose must be determined by your doctor.

Children 5 to 12 years of age—6.25 mg per kilogram (2.5 mg per pound) of body weight four times a day.

For chlorphenesin

For oral dosage form (tablets):

For relaxing stiff, sore muscles:

Adults and teenagers—800 milligrams (mg) three times a day, at first. Your doctor may decrease your dose after you begin to feel better.

Children—Use and dose must be determined by your doctor.

For chlorzoxazone

For oral dosage form (tablets):

For relaxing stiff, sore muscles:

Adults and teenagers—500 milligrams (mg) three or four times a day.

Children—125 to 500 mg three or four times a day, depending on the child"s size and weight.

For metaxalone

For oral dosage form (tablets):

For relaxing stiff, sore muscles:

Adults and teenagers—800 milligrams (mg) three or four times a day.

Children—Use and dose must be determined by your doctor.

For methocarbamol

For oral dosage form (tablets):

For relaxing stiff, sore muscles:

Adults and teenagers—1500 milligrams (mg) four times a day, at first. Your doctor may decrease your dose after you begin to feel better.

Children—Use and dose must be determined by your doctor.

For injection dosage form:

For relaxing stiff, sore muscles:

Adults and teenagers—1 to 3 grams a day, injected into a muscle or a vein. This total daily dose may be divided into smaller amounts that are given several times a day, especially when the medicine is injected into a muscle.

Children—Use and dose must be determined by your doctor.

Missed dose—If you miss a dose of this medicine and remember within an hour or so of the missed dose, take it right away. But if you do not remember until later, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage—To store this medicine:

Keep out of the reach of children.

Store away from heat and direct light.

Do not store this medicine in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.

Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

Precautions While Using This Medicine

If you will be taking this medicine for a long time (for example, more than a few weeks), your doctor should check your progress at regular visits.

This medicine will add to the effects of alcohol and other CNS depressants (medicines that slow down the nervous system, possibly causing drowsiness). Some examples of CNS depressants are antihistamines or medicine for hay fever, other allergies, or colds; sedatives, tranquilizers, or sleeping medicine; prescription pain medicine or narcotics; barbiturates; medicine for seizures; other muscle relaxants; or anesthetics, including some dental anesthetics. Do not drink alcoholic beverages, and check with your doctor before taking any of the medicines listed above, while you are using this medicine .

Skeletal muscle relaxants may cause blurred vision or clumsiness or unsteadiness in some people. They may also cause some people to feel drowsy, dizzy, lightheaded, faint, or less alert than they are normally. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert, well-coordinated, and able to see well .

For diabetic patients :

Metaxalone (e.g., Skelaxin) may cause false test results with one type of test for sugar in your urine. If your urine sugar test shows an unusually large amount of sugar, or if you have any questions about this, check with your health care professional. This is especially important if your diabetes is not well controlled.

Side Effects of This Medicine

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

Blood in urine; bloody or black, tarry stools; convulsions (seizures) (methocarbamol injection only); cough or hoarseness; fast or irregular breathing; lower back or side pain; muscle cramps or pain (not present before treatment or more painful than before treatment); painful or difficult urination; pain, tenderness, heat, redness, or swelling over a blood vessel (vein) in arm or leg (methocarbamol injection only); pinpoint red spots on skin; puffiness or swelling of the eyelids or around the eyes; sores, ulcers, or white spots on lips or in mouth; sore throat and fever with or without chills; swollen and/or painful glands; unusual bruising or bleeding; unusual tiredness or weakness; vomiting of blood or material that looks like coffee grounds; yellow eyes or skin

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

More common

Blurred or double vision or any change in vision; dizziness or lightheadedness; drowsiness

Although not all of the side effects listed above have been reported for all of these medicines, they have been reported for at least one of them. However, since all of these skeletal muscle relaxants have similar effects, it is possible that any of the above side effects may occur with any of these medicines.

In addition to the other side effects listed above, chlorzoxazone may cause your urine to turn orange or reddish purple. Methocarbamol may cause your urine to turn black, brown, or green. This effect is harmless and will go away when you stop taking the medicine. However, if you have any questions about this, check with your doctor.

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.

Revised: 11/02/2004

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